23 23 Symbols And Definitions

Fuse - A component in an electrical circuit that will open the circuit if too much current flows through it.

Switch (Normally Open): A switch that will close at a specified point (temp, press, etc.). The circle indicates that the component has screw terminals and a wire can be disconnected from it.

22 22 Switch (Normally Closed): A switch that will open at a specified point (temp, press, etc.). No circle indicates that the wire cannot be disconnected from the component.

Ground (Wired): This indicates that the component is connected to a grounded wire. The grounded wire is fastened to the machine.

21 21 Ground (Case): This indicates that the component does not have a wire connected to ground. It is grounded by being fastened to the machine.

Reed Switch: A switch whose contacts are controlled by a magnet. A magnet closes the

20 20 contacts of a normally open reed switch; it opens the contacts of a normally closed reed switch.

Sender: A component that is used with a temperature or pressure gauge. The sender

330D Excavator measures the temperature or pressure. Its resistance changes to give an indication to T the gauge of the temperature or pressure.

Electrical System Relay (Magnetic Switch): A relay is an electrical component that is activated by electricity.

19 19 It has a coil that makes an electromagnet when current flows through it. The electromagnet can open or close the switch part of the relay.

Solenoid: A solenoid is an electrical component that is activated by electricity. It has a

coil that makes an electromagnet when current flows through it. The electromagnet NBD1-UP can open or close a valve or move a piece of metal that can do work.

18 18 B6H1-UP MAGNETIC LATCH SOLENOID - A magnetic latch solenoid is an electrical component that is activated by electricity and held latched by a permanent magnet. It has two coils (latch and unlatch) EAH1-UP that make electromagnet when current flows through them. It also has an internal switch that places the latch coil circuit open at the time the coil latches. FFK1-UP17 17 JLP1-UP Harness And Wire Symbols